Meanwhile, Detective-Sergeant Harborne, following back the clue of the yellow cigarettes, in accordance with the instructions of his superior, who had elected to follow it forward, made his way to a cab-rank at the end of Finchley Road.
To a cab-minder he showed a photograph. It was from that unique negative which the Home Secretary had shown to the pseudo-Inspector Sheffield at Womsley Old Place; moreover, it was the only copy which the right honourable gentleman had authorised to be printed.
"Does this person often take cabs from this rank, my lad?"
The man surveyed it with beer-weakened eyes.
"Mr. Sanrack it is, guv'nor! Yes, he's often here!"
Harborne, who was a believer in the straightforward British methods, and who scorned alike the unnecessary subtlety of the French school, as represented by Lemage or Duquesne, and the Fenimore-Cooper-like tactics dear to the men of the American agencies, showed his card.
"What's his address?" he snapped.
"It's farther down on this side; I can't think of the number, sir," replied the other shakily. (The proximity of a police officer always injuriously affected his heart.) "But I can show you the 'ouse."
"Come on!" ordered Harborne. "Walk behind me; and when I pass it, whistle."